This invention relates to radiation measuring apparatus and is especially concerned with measurement of X-ray radiation. More especially, the invention relates to the real-time measurement and display of relatively low intensity X-ray radiation using a sensor which is sufficiently small so as not to interfere with the measurement and image-forming process commonly used during radiological procedures. The invention may also be of use in the measurement of other forms of radiation.
In some circumstances the human (or animal) body can be exposed to X-ray radiation of relatively low intensity for a long period of time, for example, when used for guidance during surgical procedures. This relatively lengthy but low level of exposure has, in some cases, led to severe skin burns. Skin doses of 400R (4Gy) are not unusual when procedures such as RF cardiac ablation or intrahepatic shunt placement are being carried out. Severe latent skin reactions have been seen following such procedures.
As a result of the potential for excessive exposure to X-ray radiation, the Food and Drug Administration (FDA) of the United States recently (Sep. 30, 1994) issued a Public Health Advisory entitled "Avoidance of Serious X-Ray Induced Skin Injuries During Fluoroscopically Guided Procedures". This advisory recommended that information be recorded in the patient's medical record to permit estimating absorbed dose to the patient's skin. The purpose of the recommendation was, of course, to encourage identification of those areas of the skin which are irradiated at levels of absorbed dose that approach or exceed a threshold for injury. This FDA advisory was followed by a second FDA advisory (Sep. 15, 1995), "Recording Information in the Patient's Medical Record That Identifies the Potential for Serious X-Ray-Induced Skin Injuries Following Fluoroscoptically Guided Procedures", which clarified which patients should have the information recorded and what information should be recorded. Both of these FDA advisories are incorporated herein by reference.
While various proposals have been made for checking the exposure of radiation in real time, the dose monitors needed to perform such checking have not heretofore been available. Such dose monitors must be sufficiently small so as not to interfere with radiological images, and should also be readable and monitorable during the exposure procedure.
There is thus a need in the art for an improved radiation measuring apparatus which can be read in real time during radiological procedures, and which is sufficiently small so as not to interfere in an unacceptable way with the radiological images resulting from the radiological procedures.
The present invention advantageously addresses the above and other needs.